To Clash can mean to disagree with someone. A clash of opinions for instance. A clash of civilizations. A conflict between peoples. You can also have a clash of colours where they simply don't work together. A Crash is when something is damaged when two or more objects collide. Perhaps a car or an aeroplane or a train. The stock market can also crash when the shares fall. Your computer may also crash.

Uprising are usually crushed. If you step on an ant, you crush it and to crush means to use overwhelming force to destroy. Clash means to argue or fight. So the uprising was crushed when the soldiers clashed with the students

Try using a dictionary for simple words like this. 1. crash (a party) = しゃしゃり出る 2. clash = 搗ち合う Very different!